This project is designed to study the role of parent training in the behavioral treatment of adoloescent obesity. Subjects, 12-15 years old, will be a minumum of 30% overweight. They will be assigned randomly to one of four experimental conditions; 1. Child Alone -Teenagers assigned to this condition will receive a 16-week program based on behavior modification priniciples for weight loss. Parents will not be involved in the treatment of these children. 2. Parent and Child Together - In this condition parents and their teenagers will meet together and will receive the identical program described in condition 1. 3. Parent and Child Separately - In this condition parents and their children will receive the behavioral weight loss program described above; in this condition, however, parents and their children will meet in separate groups led by different therapists. 4. No Treatment Control - These children will remain on a waiting list during the 16-week program and will then be offered the most effective of the three treatments described above. Multiple measures, including weight and skinfold thickness, will be used to determine the effect of parental involvement.